Tenant wants to have RV on land

[Will Reed]

So I have a tenant who recently moved out of my residence on good terms, actually helped me find some one to take there spot who has been a fantastic tenant so far. They recently came to me asking if they could rent space to put an RV on the triplex that they originally were renting in. 

So I guess my question is how much or should i even let them do this, they were a great tenant when there paid rent on time and early, then they hit hard times and couldn't afford the unit they were at any more. So I guess im looking for advice.